From de6f99723392f1c3a7bc103cba81bd9ba1d1708f Mon Sep 17 00:00:00 2001 From: Jonas Oberhauser Date: Mon, 30 Sep 2024 12:57:06 +0200 Subject: [PATCH] tools/memory-model: Legitimize current use of tags in LKMM macros The current macros in linux-kernel.def reference instructions such as __xchg{mb} or __cmpxchg{acquire}, which are invalid combinations of tags and instructions according to the declarations in linux-kernel.bell. This works with current herd7 because herd7 removes these tags anyways and does not actually enforce validity of combinations at all. If a future herd7 version no longer applies these hardcoded transformations, then all currently invalid combinations will actually appear on some instruction. We therefore adjust the declarations to make the resulting combinations valid, by adding the 'mb tag to the set of Accesses and allowing all Accesses to appear on all read, write, and RMW instructions. Signed-off-by: Jonas Oberhauser Signed-off-by: Paul E. McKenney Reviewed-by: Boqun Feng Tested-by: Boqun Feng --- tools/memory-model/linux-kernel.bell | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell index ce068700939c..dba6b5b6dee0 100644 --- a/tools/memory-model/linux-kernel.bell +++ b/tools/memory-model/linux-kernel.bell @@ -16,10 +16,11 @@ enum Accesses = 'once (*READ_ONCE,WRITE_ONCE*) || 'release (*smp_store_release*) || 'acquire (*smp_load_acquire*) || - 'noreturn (* R of non-return RMW *) -instructions R[{'once,'acquire,'noreturn}] -instructions W[{'once,'release}] -instructions RMW[{'once,'acquire,'release}] + 'noreturn (* R of non-return RMW *) || + 'mb (*xchg(),cmpxchg(),...*) +instructions R[Accesses] +instructions W[Accesses] +instructions RMW[Accesses] enum Barriers = 'wmb (*smp_wmb*) || 'rmb (*smp_rmb*) || -- 2.47.3